docs: def wnvald(insize, n, window):
      """
      Form a valid double precision window from the contents
      of a window array.
  
      http://naif.jpl.nasa.gov/pub/naif/toolkit_docs/C/cspice/wnvald_c.html
  
      :param insize: Size of window. 
      :type insize: int
      :param n: Original number of endpoints. 
      :type n: int
      :param window: Input window. 
      :type window: spiceypy.utils.support_types.SpiceCell
      :return: The union of the intervals in the input cell.
      :rtype: spiceypy.utils.support_types.SpiceCell
      """
      assert isinstance(window, stypes.SpiceCell)
      assert window.dtype == 1
      insize = ctypes.c_int(insize)
      n = ctypes.c_int(n)
      libspice.wnvald_c(insize, n, ctypes.byref(window))
      return window